Until iFixit or someone else does a tear down we won’t know how easy it will be to upgrade RAM at home. As far as the glass/monitor bonding, it’s currently no big deal on the iMac unless something has changed. But again we’ll have to see.
Unless you have the specialty tools either from Apple or iFixit. The cutter is the key, you're not opening any post 2013 iMac without one.
https://www.ifixit.com/Store/Tools/iMac-Opening-Wheel/IF145-219-4